The present invention relates generally to off-road motor vehicles, such as utility or recreational vehicles, and more particularly, to a middle axle apparatus for a utility vehicle to provide oscillatory movement for the middle axle.
Small off-road vehicles such as utility or recreational vehicles are becoming popular for recreational and other general purpose off-road usage. Such utility vehicles can be found in U.S. Pat. No. 4,706,770. These utility vehicles have found usage on golf courses and at sporting events, and are particularly adaptable for utilization on a farm. This type of flexibility in the wide variety of uses necessitates a vehicle that is highly flexible, highly maneuverable and the like. This demands a vehicle that will afford a high degree of maneuverability and ease of steering.
Steering characteristics of known utility vehicles provide poor turning performance. Known utility vehicles have turning clearance circles having a diameter greater than twenty-one feet. The use of independent front wheel suspension mechanisms on known utility vehicles, coupled with the mounting of the rack and pinion systems on the frame of the vehicle, introduces minor king pin rotations as the steering tires ride over ground undulations. Such construction reduces steering precision and can accelerate the wear of the tires on the steering axle.
Placing a load on the utility vehicle typically results in a variation in the steering performance of known utility vehicles. For example, one known embodiment having a front steering axle, a rear drive axle, and a middle drive axle carries the load placed on the vehicle on the middle and rear axles, resulting in proportionately less weight on the steering axle and a reduction in maneuverability. Accordingly, known utility vehicle construction results in a significant influence on the steering performance by the load carried on the vehicle. Preferably, loads should not change the steering characteristics for any vehicle.
Furthermore, conventional utility vehicle construction mounts the middle axle directly to the frame of the vehicle, resulting in a harsh ride characteristic and direct application of any load placed into the load bed onto the middle axle as well as the rear drive axle. Furthermore, the middle axle, in being fixed to the frame, is incapable of oscillatory movement, i.e. movement from side-to-side about a longitudinally extending pivot axis, which would further enhance the ride characteristics of the utility vehicle. It would, therefore, be desirable to enhance the ride characteristics, as well as the steering performance of utility vehicles by distributing the weight of the loads being carried in a different manner and by providing a mechanism permitting the middle axle to oscillate to better follow ground undulations.
It is therefor desirable to provide a utility and recreational vehicle that overcomes the disadvantages of the known prior art utility vehicles.
Accordingly, an important object of the present invention is to provide a middle axle support apparatus for a utility vehicle that is not directly mounted to the frame of the vehicle.
It is another object of this invention to provide a support mechanism for the middle axle on a utility vehicle to provide flotational and oscillatory movement of the middle axle relative to the frame.
It is a further object of this invention to provide support for the middle axle of a utility vehicle in such a manner as to prevent the load placed thereon from overcoming the steering operation of the front axle.
It is a feature of this invention to add a bogey beam extending longitudinally at the center line of the utility vehicle to interconnect the front and middle axles.
It is another feature of this invention that a portion of the load placed into the load bed of the utility vehicle will be distributed to the bogey beam to be re-distributed to the front and middle axles in a predetermined proportion.
It is an advantage of this invention that maneuverability of the utility vehicle is greatly increased during load bearing operations.
It is a another advantage of this invention that the middle axle provides the ability to oscillate and float relative to the frame of the utility vehicle.
It is still another advantage of this invention that the ride characteristics of a utility vehicle are improved, particularly under load bearing conditions.
It is still another feature of this invention that the loads placed on the load bed of the utility vehicle are proportionally distributed between the front steering axle and the middle drive axle of the utility vehicle.
It is a yet another advantage of this invention that the flotational movement of the middle axle provides sufficient slack in the drive mechanism to permit the chain drive to twist slightly in response to the oscillation of the middle axle.
It is yet another feature of this invention that a central support bracket pivotally connecting a support beam for the middle axle to the bogey beam allows a Rotational movement of the middle axle with the bogey beam and with longitudinally stabilizing support links.
It is a further object of this invention to provide a middle axle support mechanism for an off-road vehicle that is durable in construction, inexpensive to manufacture, carefree in maintenance, easy to assemble, and simple and effective in use.
These and other objects, features, and advantages are accomplished according to the present invention by providing a utility vehicle having a middle axle that is mounted at the end of a bogey beam for both flotational and oscillatory movement relative to the frame of the vehicle. The middle axle is restrained longitudinally by support links that are pivotally connected to the frame at a location that is forward of the rear drive axle. The middle axle is formed by a pair of stub axles interconnected by a support beam that is pivotally connected to the rearward end of the bogey beam. Vertical movement of the middle axle support wheels results in a corresponding vertical movement of the rearward end of the bogey beam and a rotation of the support beam about its pivotal connection on the bogey beam. The oscillatory movement is accomplished by a pivotal connection via a ball joint between a central support bracket mounting the transverse support beam to the longitudinally extending bogey beam.